TriCo Bancshares Condensed Financial Statements (Parent Only) - Condensed Statements of Income (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Condensed Financial Statements, Captions [Line Items]
Interest expense	$ (1,460)	$ (1,439)	$ (1,430)	$ (1,392)	$ (1,349)	$ (1,339)	$ (1,346)	$ (1,382)	$ (5,721)	$ (5,416)	$ (4,681)
Income before income taxes	20,487	19,893	14,911	17,232	18,810	21,062	18,798	14,044	72,523	72,714	44,616
Equity in net income of Tri Counties Bank:
Income tax benefit	(7,954)	(7,694)	(5,506)	(6,558)	(7,388)	(8,368)	(7,432)	(5,708)	(27,712)	(28,896)	(18,508)
Net income	$ 12,533	$ 12,199	$ 9,405	$ 10,674	$ 11,422	$ 12,694	$ 11,366	$ 8,336	44,811	43,818	26,108
Parent [Member]
Condensed Financial Statements, Captions [Line Items]
Interest expense									(2,229)	(1,977)	(1,403)
Administration expense									(725)	(814)	(2,720)
Income before income taxes									(2,954)	(2,791)	(4,123)
Equity in net income of Tri Counties Bank:
Distributed									16,758	13,304	8,270
Undistributed									29,764	32,131	20,720
Income tax benefit									1,243	1,174	1,241
Net income									$ 44,811	$ 43,818	$ 26,108